Magnetic bearings for supporting a rotor for rotation about an axis are well known in the art. Commonly, such bearings have one or more pairs of magnetic actuator cores that are assembled to form a ring centered on the axis of rotation. Typically, each of the actuator cores is formed from a stack of thin laminations of magnetic material, which serve to reduce eddy currents in the magnetic bearing. In some applications, magnetic isolation may be required between each of the actuator cores in the assembled ring. Magnetic isolation has been accomplished in the past by the insertion of non-magnetic spacers between each of the cores. The non-magnetic spacers are then welded to the cores to form the assembled ring of cores and non-magnetic spacers. The outside and inside diameters of the assembled ring are then ground to provide the accuracy required for satisfactory operation of the magnetic bearing. While such constructions have worked well for their intended purpose, there is room for improvement.
For example, each weld joining a non-magnetic spacer to one of the actuator cores is in reality a plurality of lamination to spacer welds, which may require additional inspection, thereby increasing manufacturing time and cost. Further, some laminations may be magnetically and electrically shorted together in the weld zone, thereby reducing the performance of the magnetic bearing. Additionally, material properties of the non-magnetic spacers and the actuator cores may be affected by the heat of the welding operation. Further, volatile materials trapped between the laminations of the actuator cores may prevent achievement of the vacuum environment required for some welding methods. To overcome this, extraordinary cleaning of a large number of laminations may be required, thereby further increasing manufacturing time and cost.